1. Field of the Invention
The present invention relates to a display device having a selection part which allows a user to select a power saving mode of the display device, and a method of controlling the same.
2. Description of the Related Art
In a computer system, a display device consumes most of the power that the computer system uses. Therefore, there have been proposed various methods of saving the power consumed by the display device. The display power management signaling (DPMS) standard is an international standard for display devices, and a DPMS function is recently being applied to most of the display devices.
According to the DPMS standard, a power saving function of the display device is performed according to the state of a computer main body. That is, the computer main body selectively transmits horizontal and vertical synchronous signals to the display device, and the power saving function of the display device is performed depending upon the horizontal and vertical synchronous signals output from the computer main body.
The power saving function of the display device is classified into a normal mode including a power-on state, and a power saving mode including a standby state, a suspend state, and a power-off state.
FIG. 4 shows a control block diagram of a computer system comprising a conventional display device. As shown therein, a computer main body 100 comprises a central processing unit (CPU) 103, and a video card 105 which processes data output from the CPU 103 into a video signal (Red, Green, Blue), and outputs horizontal and vertical synchronous signals to synchronize the video signal (R, G, B).
A display device 110 displays a picture based on the video signal (R, G, B) output from the computer main body 100, and comprises a signal processing part 112 which processes the video signal (R, G, B) output from the computer main body 100, and a displaying part 114 which displays the picture based on the video signal (R, G, B) processed by the signal processing part 112.
The display device 110 further comprises an AC input part 116 through which alternating current (AC) power is input, a rectifier 118 which rectifies the input AC power into direct current (DC) power, a switching transformer 120 which receives the rectified DC power, a power regulator 122 and a power output part 124 which convert and output AC power output from the switching transformer 120 into DC power, and a pulse width modulation (PWM) part 126 which transmits a pulse signal so as to control a switching operation of the switching transformer 120.
The switching transformer 120 is switched on/off in response to the pulse signal transmitted from the PWM part 126, and converts the DC power output from the rectifier 118 into AC power. The power regulator 122 converts the AC power output from the switching transformer 120 into DC power, and supplies driving powers to components of the display device 110, respectively.
A micro controller 128 controls the power regulator 122 and the PWM part 126 in response to the horizontal and vertical synchronous signals being output from the video card 105 of the computer main body 100, so as to apply a power saving mode to the display device 110.
For example, when the video card 105 outputs both the vertical and horizontal synchronous signals, the micro controller 128 transmits a normal mode signal to the power regulator 122, so as to apply electric power normally to the display device 110. When the video card 105 outputs only the horizontal synchronous signal, the micro controller 128 transmits a suspend mode signal to the power regulator 122. When the video card 105 outputs only the vertical synchronous signal, the micro controller 128 transmits a standby mode signal to the power regulator 122. When the video card 105 does not output any of the synchronous signals, the micro controller 128 controls the PWM part 126 and allows the display device 110 to be in a power-off mode state.
Thus, the power saving function of the display device 110 is performed according to the computer main body 100. Therefore, if the computer main body 100 does not have a power saving function, the display device 110 cannot perform the power saving function. Furthermore, even if the computer main body 100 has the power saving function, the display device 110 performs the power saving function after an elapse of a predetermined period of time where a user temporarily stops using the display device 110.